add REMOTE_AUTH_DISPLAYNAME setting

[llamafilm]

Fixes: #15375

Add optional setting for REMOTE_AUTH_DISPLAYNAME. If set, it will override the remote auth provider name shown on the login page.

[jeremystretch]

This change does not account for using multiple authentication backends. A much more flexible approach would be to allow an administrator to override the contents of AUTH_BACKEND_ATTRS on a per-backend basis.

[llamafilm]

How is it possible to have multiple authentication backends? REMOTE_AUTH_BACKEND is a single string variable.

[jeremystretch]

REMOTE_AUTH_BACKEND is a single string variable.

Correct, but ideally we should support multiple backends. (I thought there was an FR for this, but maybe not.) Also consider that the active backend may be changed.

[llamafilm]

Changing the backend should work fine with this.

Since that feature hasn't been defined yet, I don't think it makes sense to add extra complexity here, guessing how it might be implemented. For example, someone might wants to use 2 different backends of the same type.

[jeremystretch]

I'm sorry but this is not acceptable in its current form. Please extend it to allow overriding the values in AUTH_BACKEND_ATTRS as requested.

[jeremystretch]

@llamafilm do you intend to continue working on this, or should we release you from the FR?

[llamafilm]

I provided a very simple solution that works, and you haven't pointed out any problems with it. I'm not going to spend any more time on this to support some potential new use case that might be added in the future.

[jeremystretch]

As I said above:

This change does not account for using multiple authentication backends.

I'll go ahead and close this out.